Relativistic effect inducing drag on fast-moving dislocation in discrete system

Kim, Soon,Kim, Hokun,Kang, Keonwook,Kim, Sung Youb Elsevier 2020 International journal of plasticity Vol.126 No.-

<P><B>Abstract</B></P> <P>Phonon scattering, a dominant source of drag, is one of key issues to understand the dynamic behaviors of a dislocation. In this paper, it is found that a relativistic effect causes additional drag that is not ignorable when the dislocation's speed is comparable to the transverse shear wave speed. By considering the emission of lattice waves from the dislocation core, we theoretically derive an equation of dislocation motion wherein the relativistic effect is well considered in the frame of phonon scattering. Consequently, the relativistic drag force is characterized by two dimensionless constants that are newly defined in this study. Given that these constants depend on structural and oscillation properties of the dislocation core, a discrete nature of the core is well-reflected. Then, the solution of the equation, or the dislocation's speed, is compared with the result obtained by molecular dynamics simulation. Furthermore, the developed equation can explain a level-off behavior at high dislocation's speed by quantifying the relativistic drag force. Thus we can broaden our understanding of dislocation dynamics to fast-moving dislocations.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Relativistic effect increases the energy dissipation around the dislocation core as its speed approaches the transverse shear wave speed. </LI> <LI> The relativistic effect stems from increase of kinetic energy of the dislocation and is manifested by a spontaneous oscillation of the dislocation core. </LI> <LI> We developed a theoretical model based on discrete lattice dynamics theory and proved that the relativistic effect can be quantified by two dimensionless group parameters that are newly defined in this study. </LI> <LI> Our derived theoretical model was supported by molecular dynamics simulation of the dislocations. </LI> </UL> </P>

조기 및 후기 인공수정체 탈구 발생의 위험인자 및 임상 양상

전한솔,장준혁,권순일 대한안과학회 2023 대한안과학회지 Vol.64 No.2

Purpose: To evaluate risk factors predisposing to intraocular lens (IOL) dislocation after cataract surgery. Methods: The medical and surgical records of patients diagnosed with IOL dislocation between January 2011 and December 2021 after undergoing extracapsular cataract extraction, phacoemulsification, and phacoemulsification with pars plana vitrectomy at Hallym University Sacred Heart Hospital were reviewed retrospectively. Preoperative factors (ocular parameters and demographics) and intra-operative factors (surgery time, surgeon, and intra-operative complications) were compared according to early, late, and bilateral dislocation. Results: In 68 patents and 71 eyes, the average age at the diagnosis of dislocation was 63.3 years, and there were more males (77.5%) than females. Possible major factors predisposing to IOL dislocation were high myopia (9 eyes), retinal detachment (8 eyes), neodymium-doped yttrium aluminum garnet capsulotomy (6 eyes), and normal tension glaucoma (6 eyes). The rate of out-of-the bag dislocation was higher in early dislocation than in late. Early dislocation had a significantly older age, longer surgery time, and higher intraoperative complication rate during cataract surgery than did late dislocation. There was no difference in surgery time for late dislocated eyes compared to non-dislocated eyes. There was no difference in the incidence of dislocation between phacoemulsification and phacoemulsification with pars plana vitrectomy; there were seven eyes with prior vitrectomy only, with late dislocation. Of the seven patients with bilateral IOL dislocation, one had retinitis pigmentosa, two had retinal detachment, and one had high myopia. Bilateral dislocation patients were significantly younger at the time of cataract surgery, compared to unilateral dislocation patients. Conclusions: Early dislocation was associated with long surgery time and intraoperative complications, while late dislocation had no significant correlation with surgery-related factors. A history of vitrectomy and combined vitrectomy with cataract surgery seemed to be associated with late dislocation, but this association was not significant. 목적: 인공수정체 탈구 환자를 대상으로 위험요인 및 임상 양상에 대해서 조사하고자 한다. 대상과 방법: 본원에서 수정체낭외적출술, 초음파유화술, 유리체절제술 백내장동시수술 시행 후 2011년 1월부터 2021년 12월까지 인공수정체 탈구를 진단받은 환자들의 의무기록을 후향적으로 분석하였다. 환자의 인구학적 특성, 수술 관련 인자(수술 시간, 수술자, 술중 합병증)을 조사하였으며 조기 및 후기 탈구, 양안 탈구에 따른 위험요인의 차이를 분석하였다. 결과: 환자 68명 71안의 탈구 진단 당시 평균 연령은 63.3세였으며 남자(77.5%)가 여자보다 많았고 고도근시(9안), 망막박리(8안), neodymium-doped yttrium aluminum garnet 후낭절개술(6안), 정상안압녹내장(6안)이 보고되었다. 조기 탈구가 후기 탈구에 비해낭외탈구의 비율이 높고, 백내장수술 당시 연령이 높고 수술 시간이 길었으며, 술 중 합병증 발생도 높았으나 후기 탈구는 정상 대조군과 비교하여 수술 시간의 차이는 없었다. 유리체절제술과 백내장동시수술은 초음파유화술과 탈구 발생률의 차이가 없었으며 유리체절제술을 받은 눈이 후기 탈구에서만 7안 있었다. 양안 탈구안 7명 중 색소망막염(1명), 망막박리(2명), 고도근시(1명)이 보고되었으며 단안 탈구보다 연령이 낮았다. 결론: 인공수정체의 조기 탈구는 술 중 합병증과 연관이 있으나 후기 탈구는 술 중 합병증보다는 환자의 기저 특성과 상관관계를보였다. 유리체절제술은 조기 탈구보다는 후기 탈구와 연관이 있어 보였으나 통계적으로 유의하진 않아 추가 연구가 필요할 것으로보인다.

Atomistic simulation analysis of the effects of void interaction on void growth and coalescence in a metallic system

Z.X. Wen,J.P. Wang,Y.W. Wu,K.J. Zhou,Z.F. Yue 한국물리학회 2018 Current Applied Physics Vol.18 No.6

Material deformation caused by the interaction between defects is a significant factor of material fracture failure. The present study employs molecular dynamics simulations of single-void and double-void crystalline Ni atomic systems to investigate inter-void interactions. Furthermore, simulations showing the evolution of dislocations for three different crystallographic orientations are conducted to study the void growth and coalescence. The simulations also consider the effect of the radius of the secondary void on dislocation evolution. The results show that double-void systems are more prone to yield than single-void systems. Further microstructural analysis indicates that the interaction between voids is realized by dislocation reactions. The simulation results of the dislocation evolution of the three orientations reveal that a relationship exists between the evolution of the dislocation density and the stress-strain curve. At the initial stage of dislocation, the dislocation grows slowly, and consists of Shockley partial dislocation. The dislocation growth rate then increases significantly in the sharply declining stage of the stress-strain curve, where most of dislocations are Shockley partial dislocation. Analysis of the dislocation length during the overall simulation indicates that the dislocation length of the [110] orientation is the longest, followed by that of the [111] orientation and the [100] orientation, which has the shortest dislocation length.

Evaluation of Articular Eminence Morphology in Patients with Spontaneous Temporomandibular Joint Dislocation Using Cone Beam Computed Tomography

김지후,박현정,서요섭,유지원,안종모 대한안면통증구강내과학회 2022 Journal of Oral Medicine and Pain Vol.47 No.1

Purpose: This study aimed to broaden our understanding of the predisposing factor and treatment of dislocation by analyzing and evaluating the morphology of the articular eminence (AE) in subjects with temporomandibular joint (TMJ) dislocation using cone beam computed tomography (CBCT). Methods: The subjects were divided into two groups: dislocation (31 subjects) and control (32 subjects). CBCT was used to examine 126 TMJs in 63 subjects (26 males, 37 females). The height, width, and posterior slope of the AE were measured in the parasagittal plane. The posterior slope was measured using the “top-roof line angle (TR angle)” method and the “best-fit line angle (BF angle)” method. The AE on the left side (AEL) and the AE on the right side (AER) of the subjects in the dislocation group were separately analyzed and compared with the control group after taking measurements. The average value of both sides was used when comparing with subjects with bilateral dislocation. Results: Dislocations were more frequent in females (67.7%) than in males (32.3%). The dislocation group showed a gentler TR angle than the control group in the AER and in the average of AE on the both sides (AEB). The same group also showed a wider AE in the AEL and the AER (p<0.05). In subjects with unilateral dislocation, the width of the AE with dislocation was narrower and the TR angle and BF angle was steeper than the other side without dislocation (p<0.05). Conclusions: In subjects with unilateral TMJ dislocation, the posterior slope of the AE is steeper, and the width is narrower at the site of dislocation compared to the site without dislocation. However, in subjects with bilateral TMJ dislocation, AEB were wider, and the mean value of the posterior slope of AEB was gentler than that of the control group.

일차성 인공 고관절 치환술 후 고관절 탈구 발생의 위험성

손원용 ( Won Yong Son ),문준규 ( Joon Kyu Moon ),한상환 ( Sang Wwhan Han ),양재혁 ( Jea Hyuk Yang ),유순용 ( Soon Yong Yoo ) 대한고관절학회 2006 Hip and Pelvis Vol.18 No.4

목적: 후외방 도달법 및 후방 관절낭 봉합술을 시행한 일차성 인공 고관절 치환술 후 고관절 탈구 발생률과 그 위험 요소에 대해서 알아보고자 한다. 대상 및 방법: 1998년 1월부터 2003년 5월까지 본원에서 시행한 후외방 도달법 및 관절낭 봉합술을 이용한 일차성 인공관절 치환술을 시행한 환자 중, 술 후 1년 이상 추적 관찰이 가능하였던 211예 대상으로 후향적 연구를 시행하였다. 탈구의 위험요인 분석으로서 수술 전 환자의 상태와, 수술적 요소로 나누어 탈구군 6예와 비탈구군 120예를 임의 선정하여 비교하였다. 수술 전 요인은 환자의 연령, 성별, 고관절의 기저 질환, 전신 질환, 음주병력 등을 조사하였고, 수술적 요인으로 인공삽입물의 요소에 대해 비교하였다. 인공 삽입물은 수술 직후의 방사선 사진상의 비구 컵의 전염각 및 경사각, 술 후 하지 부동, 대퇴 스템의 전염각 및 전염각의 합을 측정하여 비교하였다. 통계학적인 검정은 Fisher`s Exact 테스트 및 T 테스트를 이용하였다. 결과: 탈구는 총 211예 중 6예(2.8%)에서 발생하였고 전방 탈구 4예(1.9%) 후방 탈구 2예(0.9%)였다. 탈구 발생시기는 술 후 평균 6.1일이었고, 5예에서는 보존적 치료, 1예에서는 수술적 치료를 시행하였다. 탈구군과 비탈구군과의 비교에서는 수술 전 환자로 인한 탈구 인자로 설정 했던 연령, 성별, 기저질환, 전신질환, 음주력, 수술 첫날의 Hemo Vac의 양, 수술 전 하지 부동 중 음주력 및 신경학적인 질환을 제외하고 모두에서 수술 후 탈구발생과 통계적 연관성을 보이지 않았다. 그러나 전방 탈구군에서 비구 전염각과 대퇴 스템의 전염각의 합은 비탈구군과 비교 시 19도 이상의 차이를 보였다. 결론: 후외방 도달법 후 시행한 후방 관절낭 봉합술은 술 후 탈구 발생률을 줄일 수 있고, 인공 고관절 치환술후 비구 컵 및 대퇴부품의 전염각의 합이 탈구 발생에 중요한 요소가 될 것으로 사료된다. Purpose: Dislocation is the second most common cause of failure, after implant loosening, in revisional THA (Total hip arthroplasty), and its evaluation and treatment still remain controversial issue. This study was undertaken to evaluate the risk factors after THA using the posterolateral approach and posterior soft tissue repair. Materials and Methods: Between January 1998 and May 2003, 211 consecutive primary total hip replacement arthroplasties using the posterolateral approach and posterior soft tissue repair were performed by the same surgeon. To compare the dislocation groups (6 cases) with the non-dislocation groups (205 cases), we randomized 120 of the non-dislocation cases. The risk factors for hip dislocation were categorized into patient factors and surgical factors. Patient factors included gender, age, preoperative diagnosis, underlying systemic disease, and alcoholic history. Surgical factors included position of the component (acetabular version and inclination, femoral anteversion), leg length discrepancy, and sum of anteversions of the cup and stem. Their parameters were measured on postoperative radiographs. Statistics were performed with Fishe`s Exact test and T test. Results: Dislocations occurred at an overall incidence rate of 2.8% (6/211cases). There were 4 (1.9%) cases of anterior dislocations and 2 (0.9%) cases of posterior dislocations. Dislocations occurred on average at postoperative day 6.1 and all dislocated hips were reduced with the closed method, except for one case that was treated surgically. There was no statistical significance in patient factors between the two groups, except for neurologic disease and alcoholic history. However, the sum of the acetabular and femoral anteversions in the anterior dislocation group was larger than that of the non-dislocation group by approximately 19 degrees. Conclusion: Our results demonstrated that by using the posterior approach and repair of soft tissue, the posterior dislocation rate after total hip replacement arthroplasty can be reduced and the sum of the acetabular and femoral anteversions had more influence on dislocations after THAs than did either anteversion alone.

Magnetic resonance imaging analysis of rotator cuff tear after shoulder dislocation in a patient older than 40 years

Jung-Han Kim,Jin-Woo Park,Si-Young Heo,Young-Min Noh 대한견주관절의학회 2020 대한견주관절의학회지 Vol.23 No.3

Background: This study was designed to evaluate characters of the rotator cuff tear (RCT) recognized after primary shoulder dislocation in patients older than 40. Methods: From 2008 to 2019, patients who visited two hospitals after dislocation were retrospectively reviewed. Inclusion criteria were patients over 40 who had dislocation, with magnetic resonance imaging (MRI) undergone. Exclusion criteria were patients who lost to follow-up, combined with any proximal humerus fracture, brachial plexus injury, and previous operation or dislocation history in the ipsilateral shoulder. Also patients who had only bankart or bony bakart lesion in MRI were excluded. We evaluated RCTs that were recognized by MRI after the primary shoulder dislocation with regard to tear size, degree, involved tendons, fatty degeneration, the age when the first dislocation occurred, and the duration until the MRI was evaluated after the dislocation. Results: Fifty-five RCTs were included. According to age groups, the tear size was increased in coronal and sagittal direction, the number of involved tendons was increased, and the degree of fatty degeneration was advanced in infraspinatus muscle. Thirty-two cases (58.2%) conducted MRI after 3 weeks from the first shoulder dislocation event. This group showed that the retraction size of the coronal plane was increased significantly and the fatty accumulation of the supraspinatus muscle had progressed significantly. Conclusions: Age is also a strong factor to affect the feature of RCT after the shoulder dislocation in patients over 40. And the delay of the MRI may deteriorate the degree of tear size and fatty degeneration.

인공 고관절 전치환술 후 탈구

김준식 ( Jun Shik Kim ) 대한고관절학회 2011 Hip and Pelvis Vol.23 No.2

The prevalence of reoperation due to dislocation after total hip arthroplasty ranks high because of aseptic loosening, periprosthetic fracture and infection. Dislocation occurs in 0.5% to 4% of the cases in a year after primary total hip arthroplasty. The risk of dislocation is influenced by the position of the components, the surgical approach, the surgical techniques, the design of the prosthesis, the underlying diagnosis and the patient`s compliance with restrictions. A better understanding of the etiology of dislocation and refinements of surgical techniques have led to a decrease in the rate of dislocation over time. Although most dislocations after total hip arthroplasty are a single episode that can be managed nonoperatively, some patients require surgical intervention to treat recurrent dislocation. The choice of surgical technique to manage recurrent dislocation depends on the etiology of the problem. The surgical options available for the treatment of recurrent dislocation consist of component revision, modular component exchange, use of a larger femoral head, soft tissue reinforcement, advancement of the greater trochanter, bipolar arthroplasty and use of a constrained liner.

경전자 도달법을 이용한 일차성 인공 고관절 전치환술 후 고관절 탈구 발생의 위험 요인

황규태 ( Kyu Tae Hwang ),김영호 ( Young Ho Kim ),김이석 ( Yee Suk Kim ),봉현종 ( Hyun Jong Bong ),최일용 ( Il Yong Choi ) 대한고관절학회 2010 Hip and Pelvis Vol.22 No.1

Purpose: We wanted to evaluate the risk factors that predispose a patient to dislocation after undergoing primary total hip arthroplasty with the transtrochanteric approach. Materials and Methods: Between July 1995 and May 2007, 593 consecutive total hip arthroplasties using the trantrochanteric approach were performed. A matched comparative study was performed for the dislocated group(18 hips) and the non-dislocated control group(18 hips). The patient-related factors and mechanical factors were retrospectively reviewed to evaluate the risk factors for dislocation. Results: Dislocation occurred in 18 hips(3.04%). The mean age was 57.1 years in the dislocated group and 55.2 years for all of the patients (p>0.05). Statistical analyses of the BMI, inclination and anteversion of the cup, lowering of the hip center, a leg length discrepancy, the size of the femoral head and nonunion of the greater trochanter revealed no significant differences between the two groups. Nonunion of the greater trochanter was observed in 16 hips(2.84%). The risk of dislocation was 8.5 times higher in the patients with excessive alcohol intake (p<0.05). The combination of more than 3 risk factors significantly affected the incidence of dislocation after total hip arthroplasty (p<0.05). Conclusion: After primary total hip arthroplasty with the transtrochanteric approach, in the cohort of this study, excessive alcohol intake was the main risk factor for dislocation and a combination of risk factors contributed to dislocation.

족관절의 골절-탈구에 대한 임상적 고찰

김지훈,송재광,서진수,Kim, Ji Hoon,Song, Jae Gwang,Suh, Jin Soo 대한족부족관절학회 2013 대한족부족관절학회지 Vol.17 No.3

Purpose: We evaluate clinical manifestations and radiologic features of ankle fracture & dislocation, as well as the usefulness of computed tomography on posterior ankle fracture & dislocation to study factors contributing to ankle fracture & dislocation. Material and Methods: Ankle dislocation was defined as the center of talar body being translated over the cortex of tibia on AP or lateral view on simple X-ray. Surgical treatments of 30 patients from January 2007 to March 2012 were categorized according to the injury mechanism, the direction of dislocation and fracture site. Joint involvement of posterior malleoalr fracture was evaluated through simple x-ray and computed tomography. We treated surgically if posterior malleolus fracture involves more than 25% of dital tibial articular surface. Thereafter, clinical outcomes were identified through radiographs and by using the AOFAS score. Results: The mean age was 42(13-78) years old, and slip down was the most common injury mechanism (13 cases). Car accident (6 cases) and fall accident (4 cases) were the next frequently found injury mechanisms. As for the types of ankle fracture, posterior fracture and dislocation (21 cases, 43.3%) was most commonly found. Out of these 21 cases, 15 cases involved trimalleolar fracture, and 19 cases were associated with posterior malleolar fracture. Danis-weber type B and C patients were 11 cases and 10 cases respectively. Articular involvement of posterior malleolar fracture turned out to be average 27.9%(5.1%~49.1%) on simple x-ray. The rate was evaluated as average 31.7%(12.6%~55.3%) on computed tomography which was conducted 15 times, and led us to more meaningful data. Conclusion: Anterolateral fracture and dislocation often accompanied open dislocation. Posterior fracture dislocation was most commonly found. Posterior malleolus was an important factor that ensures posterior stability of the ankle joint. Computed tomograph is useful to evaluate the articular involvement of posterior malleolar fracture.

탈구를 동반한 족관절 골절에서 수술적 치료 후 최소 2년 추시 결과

조승환,이준영,조성원,박치형,Jo, Sueng-Hwan,Lee, Jun-Young,Cho, Sung-Won,Pak, Chi-Hyoung 대한족부족관절학회 2013 대한족부족관절학회지 Vol.17 No.1

Purpose: In previous study, the frequency of osteoarthritis and discomfort were high in ankle fracture-dislocation but detail results about ankle fracture-dislocation has rarely been investigated. In this study, we retrospectively analyze the outcome of the operative treatment of ankle fracture with dislocation for over-2 years follow up. Materials and Methods: There were 47 cases of ankle fracture-dislocation in our hospital from March 2007 to May 2010. We investigated 20 patients who underwent operation and were possible for over-2 years follow up. The result was estimated with the direction of dislocation, fracture type, the time of bone union and post-traumatic osteoarthritis with plain radiologic images. In clinical assessment, we statistically evaluated the function and pain through AOFAS score and Olerud & Molander scoring system. Results: By Lauge-Hansen classification, there were 13 cases(65%) of pronation-external rotation and 6 cases(30%) of supination-external rotation, 1 case(5%) of supination-adduction. AOFAS score was 85.5, and Olerud & Molander score was "excellent" in 8 cases, "good" in 5 cases, "fair" in 3 cases and "poor" in 4 cases. Postoperative complications in 4 cases revealed post-traumatic arthritis. All kinds of lateral dislocation of ankle fracture was 15 cases and the most common. Of these, all 3 cases, anterolateral dislocation showed post-traumatic osteoarthritis. Conclusion: In ankle fracture-dislocation, post-traumatic osteoarthritis occurred in 4 of 20 patient(20%). Especially, the possibility of post-traumatic osteoarthritis was more in cases of anterolateral or lateral dislocation. So, it must be needed that deliberate examination, for example, preoperative MRI and sufficient explanation to patient. Also, we have to follow up the patients carefully.